Modern motor graders are provided with cabs that may be sealed to afford an air-conditioned and dust free controlled environment for the operator. This is particularly important because of the enormous amounts of dust that are produced when grading is carried out in fine, dry soil. Commonly, such motor graders have a longitudinal main frame provided by an I beam beneath which the grader blade is mounted, and the cab is at the rear of the I beam with a windshield above the beam and forward observation windows (often called quarter windows) in the front wall which flank the beam so the operator can observe the grader blade and the graded area. Conventional windshield washers and windshield wipers are provided for the windshield and for the windows to assure clear visibility for the operator.
In pleasant weather, some operators prefer to operate with the side door or side windows open to enjoy the fresh air, and this creates a problem of dust collecting in the cab and particularly upon the inside surface of the forward observation windows where it obscures the operator's view of the blade and the graded area. This can result in less efficient grader operation and lower quality grading.
There is also an advantage in having a hinged window in a side door of a cab to afford "anti-draft" ventilation.
In either location, a locking mechanism is essential to secure the window in any desired position between fully closed and fully open.